Mikado Sanzenin is a student at Saint Kohlhoz Gakuen and the male half of the Golden Pair, a legendary duo in the world of martial arts figure skating. He forms this team with his partner, Azusa Shiratori. Physically, he is tall and strikingly handsome, with a refined and beautiful face that attracts many admirers. Beneath this polished exterior lies an intensely narcissistic and lecherous personality. His mind is almost entirely occupied with thoughts of himself and women, a trait that leads other characters to label him a chronic lecher. He openly admits that his head is full of such ideas and shows little shame about it. His primary motivation is to pursue and conquer beautiful women, often using his skating skills and charm to break up established couples. He approaches romantic conquests as a competitive sport, and his tactics are underhanded and manipulative.

In the story, Mikado Sanzenin appears during the martial arts figure skating arc as a rival to Ranma Saotome and Akane Tendo. He accidentally becomes Ranma's first kiss when he encounters the female form of Ranma on the ice and, in a moment of theatrical flair, kisses her in front of a crowd. This incident enrages Ranma and sets the stage for their conflict. Mikado's role is that of a charismatic but villainous antagonist. He schemes to win Akane's affection and orchestrate a breakup between her and Ranma, partly out of genuine interest in her and partly to prove his superiority. He challenges the pair to a martial arts skating match, with Akane as the prize. His arrogance and confidence are central to his role, as he believes his skills and tactics are unbeatable.

Key relationships define his character arc. With his partner Azusa Shiratori, the dynamic is one of mutual disdain and dysfunction. He considers her a foolish girl and frequently calls her such, while she is equally self-centered and physically abusive toward him. Their partnership is based on convenience and shared success rather than any genuine affection. With Ranma, Mikado is a rival and antagonist. Their conflict is personal, stemming from the forced kiss and the subsequent battle for pride and for Akane. With Akane, he is a pursuer, attempting to charm and kidnap her, viewing her as a prize to be won.

Mikado experiences limited but notable development. He begins as an arrogant and undefeated champion who believes his beauty and skill make him invincible. His defeat at the hands of Ranma and Akane is a profound shock to his ego. During the climactic match, he uses a technique called the Dead Spirit's Bon Dance, a powerful spin that he claims no one has ever escaped. In truth, Ranma counters every move, landing over five hundred hits during the dance, leaving Mikado standing but unconscious from the cumulative damage. He is also outsmarted during his Farewell Merry-Go-Round maneuver, as Ranma refuses to release Akane's hand, foiling his plan. After this defeat, he and Azusa leave together, and he does not reappear in the main story. The loss humbles him in a practical sense, though his fundamental nature remains unchanged.

Notable abilities center on his mastery of martial arts figure skating. He possesses incredible speed and agility on the ice, demonstrated by his ability to defeat one hundred opponents in a hundred-man sparring drill in just nine seconds. His signature technique is the Dead Spirit's Bon Dance, a rapid spin that leaves opponents disoriented and vulnerable. He also employs the Farewell Merry-Go-Round, a coordinated attack with Azusa designed to force an enemy pair to separate by tempting the male partner to let go of his female partner. Beyond his physical skills, his most potent weapons are his charisma, good looks, and manipulative nature, which he uses to seduce and psychologically break his opponents. He is the strategic brain of the Golden Pair, cool and calculating, in contrast to his partner's impulsive and childish behavior.